Water Conservation and Pollution: Impacts on Hydrological Cycle and Human Activities, Study notes of Environmental Science

Download Water Conservation and Pollution: Impacts on Hydrological Cycle and Human Activities and more Study notes Environmental Science in PDF only on Docsity! 1 Announcements • Extra credit movies next Thursday • Today: Water conservation and pollution – Hydrological cycle – Water exploitation – Water pollution Dust bowl: 1930 – 1936 South Dakota Oklahoma 2 What caused the dust bowl? • Settlement during unusually wet period • Farming without crop rotation • Several years of drought • Solution: Ogallala Aquifer (tapped extensively after WWII) Water sources Pools of water Volume (km3) % Atmosphere 13,000 0.0009 Fresh water 2,500,000 0.18 Groundwater 8,200,000 0.6 Ice 27,000,000 1.9 Oceans 1,350,000,000 97.6 Sum 1,380,000,000 100 Hydrologic Cycle • Evaporation & transpiration • Condensation & precipitation • Purification • Transportation 5 Water conservation First three photos from: http://www.ers.usda.gov Percolation loss at low spot in furrow Sprinklers drip systems 50% U.S. systems gravity flow Water conservation at home • Tips for conserving – Don’t grow a lawn – New toilets – Short showers – New clothes washer – Use a dishwasher – Stop leaks Water pollution • Solid Waste (plastics, cigarette butts) • Organic contaminants – BOD: Biochemical Oxygen Demand – PAH: Polycyclic Aromatic Hydrocarbons – Halogenated Hydrocarbons (adding Cl, F, Br) • Heavy metals (Pb, Cr, Cu, etc.) • Organo-metals: Methyl-Hg (Neurotoxin), TBT (immunity) • Pathogens (bacteria, viruses) • Water property changes (e.g., temperature) • Excess nutrients 46,000/mi2 6 Water pollution sources • Primary sources – Runoff & discharges – atmospheric deposition • Point sources • Nonpoint sources From Garrison (2002) Oceanography Water pollution fates Nutrient and metals profiles from the ocean Fate: Sorption and accumulation in sediments & bioaccumulation Fate of DDT 7 Biomagnification Water pollution effects • Nutrients and eutrophication – Nutrients limit productivity • Key limiting nutrients: nitrogen and phosphorus – Excess nutrients act as pollutants • Steps: – Increased N or P – Increased phytoplankton productivity – Decreased water clarity – Mixing rates low: - phytoplankton sink to bottom - respiration consumes oxygen - aerobic organisms emigrate or die Pollution and population size • N input to coastal zone correlated with population size Plot from Howarth et al. (2000)